A premixed dual fuel burner with a tapering injection component for main liquid fuel

ABSTRACT

A premixed dual fuel burner includes a burner head, a burner interior elongated along a main axis and having an upstream side enclosed by a swirler and a downstream side enclosed by a premixing section, and an injection component. The burner head and sides are serially arranged. The swirler includes an inlet section for introducing air and a main gas fuel. The injection component has a tapering structure positioned along the main axis which extends from the burner head into the burner interior. The injection component tapers from a burner head side and an injection side along the main axis. At the injection side a liquid fuel outlet introduces a main liquid fuel into the burner interior. The injection side is disposed in the burner interior. At least one of the at least one liquid fuel outlet is at a side of the injection side of the injection component.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International ApplicationNo. PCT/EP2016/068139 filed Jul. 29, 2016, and claims the benefitthereof. The International Application claims the benefit of EuropeanApplication No. EP15181707 filed Aug. 20, 2015. All of the applicationsare incorporated by reference herein in their entirety.

FIELD OF INVENTION

The present invention relates to turbomachine components and moreparticularly to a burner for a dual fuel based combustion chamber for aturbomachine.

BACKGROUND OF INVENTION

In modern day turbomachines, dual fuel i.e. a liquid fuel and a gaseousfuel, are used advantageously as main fuels in many applications forexample in Lean Premix combustions, Dry Low NO_(X) combustions, and soand so forth. In present day turbomachines that employ dual fuelcombustion techniques, a burner assembly in a combustion sectionincludes a burner head connected to a swirl generator or swirler that inturn is connected to a mixer or premixing pathway or section. The burnerassembly is connected to or assembled with a combustion chamber. Incombustion section of the turbomachines that use the dual fueltechniques, the main fuels, distinct from pilot fuel supplies, aremostly both gaseous and liquid.

The basic technique in such dual fuel combustions is to premix the mainfuel with air from a compressor of the turbomachine before igniting thecombustion mixture, i.e. mixture of the air from the compressor and themain fuel, in the combustion chamber. Usually the air from thecompressor is mixed with the main gaseous fuel, either inside theswirler or just before introduction into the swirler, and then swirledby the swirler to create a swirling flow of the air and the main gaseousfuel. This swirling flow of the pressurized air from the compressor andthe main gaseous fuel then enters from the swirler into the premixingsection. At the premixing section the pressurized air from thecompressor and the main gaseous fuel are allowed to mix well beforeexiting into the combustion chamber or the combustion space where thecombustion mixture undergoes combustion.

In dual fuel combustors, or combustion sections, the main liquid fuel isdischarged by a nozzle positioned at the burner head. The main liquidfuel after exiting the nozzle, advantageously in atomized form, entersthe swirler and then continues into the premixing section and finallyinto the combustion chamber where the main liquid fuel participates inthe combustion reaction.

Also known are burners with a central fuel lance to provide for gaseousand/or liquid fuel. One configuration of a cylindrical central fuellance is known from the patent publication US 2010/0273117 A1.

Further, U.S. Pat. No. 5,791,894 A shows a conical inner body within apremix burner, to generate a swirl about an axis by swirling of a mediumaround the inner body. The inner body may comprise optionally also abore to provide liquid fuel and/or air to a front region of thecombustion space.

However, there are some disadvantages in the scheme of presently knowndual fuel burners and as described above. Firstly, discharging of themain liquid fuel at the burner head interferes with the swirl generationperformed by the swirler by increasing the aerodynamic disturbancesinside the swirler. Furthermore, the aerodynamic disturbances alsoadversely affect an axial flow of the combustion mixture and/or itscomponents, i.e. flow of the combustion mixture and/or its constituentsfrom a burner head side of the burner towards the combustion chamber.Secondly, since the main liquid fuel is discharged before the swirler orjust at the beginning of the swirler, in some cases parts of the mainliquid fuel get deposited on surfaces of inside walls of the swirlerand/or the premixing section. This deposition of the main liquid fuelresidues leads to clogging of the interiors of the swirler andespecially the interiors of the premixing section. The clogging resultsin loss of efficiency and in most cases the turbomachine operation isrequired to be stopped to clean the main liquid fuel residues depositedon surfaces of inside walls of the swirler and/or the premixing section.

Furthermore, as a result of the clogging and the aerodynamicdisturbances, as mentioned above, a flow of combustion mixture and/orcomponents of the combustion mixture is jeopardized which leads intoincreased possibility of formation of recirculation zones within burnerinteriors such as the premixing section. The formation of therecirculation zones within the burner interiors is undesirable, as itmay result into overheating of the burner components for example thepremixing section and/or the swirler. A continued problem of overheatingover an extended period of time may result into damaging of the parts ofthe burner components i.e. the premixing section, the swirler, etc.Moreover, as a result of the formation of the undesired recirculationzones within the premixing section, efficiency of the turbomachines inoperation is reduced.

SUMMARY OF INVENTION

An object of the present technique is to obviate the above mentioneddisadvantages and to ensure that recirculation zones for the combustionare formed at a desired spatial position in the combustion chamber orthe combustion space. It is undesirable to allow formation of therecirculation zone within the premixing section of the burner. Achievingthis object increases the combustion efficiency and thus the efficiencyof the overall turbomachine, elongates operational life of thecomponents of the burner and associated structures that may otherwiseget over heated due to formation or extension of recirculation zones atundesirable spatial positions within the burner interiors, andstabilizes the combustion reaction due to control on the recirculationzone formation and its spatial position in the combustion chamber.

The above objects are achieved by a premixed dual fuel burner of thepresent technique. Advantageous embodiments of the present technique areprovided in dependent claims. Features of the independent claim may becombined with features of dependent claims, and features of dependentclaims can be combined together.

According to the present technique, a premixed dual fuel burner for acombustion chamber of a turbomachine is presented. The premixed dualfuel burner, hereinafter referred to as the burner, includes a burnerhead, a burner interior, a swirler, a premixing section and an injectioncomponent. The swirler is arranged in series between the burner head andthe premixing section. The burner head includes a burner head end. Theburner interior is elongated along a main axis of the burner and isformed of an upstream side and a downstream side. The upstream side isdisposed between the burner head and the downstream side. The upstreamside is fluidly connected to the downstream side, i.e. the upstream sideand the downstream side are continuous and together form the burnerinterior. A part of the burner interior enclosed by the swirler is theupstream side of the burner interior and the other part of the burnerinterior enclosed by the premixing section is the downstream side of theburner interior. The swirler includes an inlet section. The inletsection is configured to introduce air and a main gas fuel into theburner interior. The premixing section has a burner outlet through whichthe premixing side is configured to be arranged or fixed or assembledwith the combustion chamber such that the downstream side is fluidlyconnected to the combustion chamber.

The injection component has a tapering structure positioned along themain axis. The tapering structure of the injection component extendsfrom the burner head into the burner interior. The injection componenthas a burner head side and an injection side. The injection componenttapers from the burner head side to the injection side along the mainaxis. The injection component includes at least one liquid fuel outletat the injection side. The injection component is configured tointroduce a main liquid fuel into the burner interior through the atleast one liquid fuel outlet. The main liquid fuel introduced in theburner interior by the injection component via the liquid fuel outlet isdirected towards the combustion chamber. The injection side of theinjection component is disposed in the burner interior.

Besides, at least one of the at least one liquid fuel outlet is at aside i.e. a side face of the tapering—of the injection side of theinjection component. Thus, the liquid fuel outlet is angled in respectof an axial direction of the burner.

The injection component is particularly a fuel lance.

The tapering structure of the injection component minimizes aerodynamicdisturbances in the burner interior, and thus ensuring efficientfunctioning of the swirler in generating swirl which in turn aids inachieving a desired spatial position of a central recirculation zone,advantageously the central recirculation zone or the main recirculationzone is formed and limited completely within the combustion chamber, andthus minimizing possibilities of a flashback into the burner interior.Furthermore, the tapering structure of the injection componentfacilitates an axial velocity, i.e. along the main axis, of thecombustion mixture i.e. the main fuel gas and the air mixture exitingfrom the swirler into the premixing section and continuing further intothe combustion chamber. The facilitation of the axial velocity resultsfrom directed flow of the combustion mixture and/or its constituentsalong the tapering structure. The tapering form of the injectioncomponent acts as a guide to the flow of main gas fuel and airfacilitating the axial flow direction. This also helps in achieving thedesired spatial position of the recirculation zone, which isadvantageously positioned in the combustion chamber and outside thepremixing section. The positioning of the recirculation zone outside thepremixing zone and within the combustion chamber minimizes possibilitiesof a flashback into the burner interior for example into the premixingsection interior.

Furthermore, by introducing the main liquid fuel via the liquid fueloutlet on the injection component extending into the burner interior andby directing the main liquid fuel towards the combustion chamber, it isensured that deposition of residues of the main liquid fuel is minimizedin inner walls of the swirler and/or the premixing section, and thusclogging of the burner cavity enclosed by the swirler and/or thepremixing section is at least partially prevented which in turn leads toproper swirl action by the swirler and/or proper fuel premixing actionby the premixing section and which subsequently also helps in formationof the recirculation zone at the desired spatial position and inincreasing efficiency of the turbomachine.

In an embodiment of the burner, the tapering structure of the injectioncomponent is a conical structure. The conical structure hasadvantageously a regular geometrical shape i.e. the conical structure issymmetrical about a longitudinal axis of the conical structure. Thetapering of the structure is smooth and gradual. The regular conicalstructure helps in further reduction of the aerodynamic disturbances inthe burner interior. Moreover, the conical shape being a regular shapeis easy to manufacture and assemble.

In another embodiment of the burner, the tapering structure of theinjection component is arranged coaxially to the main axis. Thelongitudinal axis of the conical structure overlaps with the main axis.This adds symmetry to the burner interior and this facilitates thefurther reduction of the aerodynamic disturbances in the burnerinterior.

In another embodiment of the burner, a first distance is between 20% and80% of a second distance. The first distance is a distance measuredalong the main axis between the at least one liquid fuel outlet and theburner head end. The second distance is a distance measured along themain axis between the burner outlet of the premixing section and theburner head end, in other words a length of the burner interior alongthe main axis. Thus, the main liquid fuel is transported, confinedwithin the injection component, at least partially through parts of theburner interior that are enclosed by the swirler and/or the premixingsection and is delivered into the burner interior at a desired positionwithin the burner interior depending on a ratio of the first and thesecond distances. By maintaining a proper ratio of the first and thesecond distances, the main liquid fuel is ejected or injected out intothe burner interior at a desirable position in the burner interior thusat least partially decreasing the risk of spraying the liquid fuel onsurfaces of the inner walls of the swirler and/or the premixing section.

In another embodiment of the burner, the injection component isconfigured to be longitudinally adjustable along the main axis such thata position of the at least one liquid fuel outlet of the injectioncomponent is changeable from a first location along the main axis to asecond location along the main axis. Thus a desirable position in theburner interior to eject or inject out the main liquid fuel can beadjusted during an operation of the turbomachine and/or may be set asdesired between two operations of the turbomachine.

In another embodiment of the burner, the at least one liquid fuel outletis positioned in the upstream side of the burner interior. This providesan embodiment in which, if so desired for a particular mode of operationof the turbomachine, the main liquid fuel can be injected out of theliquid fuel outlet before the premixing section.

In another embodiment of the burner, the at least one liquid fuel outletis positioned in the downstream side of the burner interior. Thisprovides an embodiment in which, if so desired for a particular mode ofoperation of the turbomachine, the main liquid fuel can be injected outof the liquid fuel outlet into the burner interior enclosed by thepremixing section. Furthermore, this embodiment ensures that spraying ofthe liquid fuel on surfaces of the inner wall of the swirler and atleast a part of the surfaces of the inner wall of the premixing sectionare minimized.

In another embodiment of the burner, one of the at least one liquid fueloutlet is at an end of the injection side of the injection component,particularly at a tip of the injection component. The end is the mostaxial position of the injection component. This ensures that a spray ora fluid stream of the main liquid fuel is directed along the main axistowards the combustion chamber. According to the invention a further onealso called “first additional outlet”—of the at least one liquid fueloutlet is at a side of the injection side of the injection component.The first additional outlet is configured to introduce the main liquidfuel into the burner interior. The first additional outlet is at a sideof the injection side of the injection component. This provides anadditional direction in which an additional spray or an additional fluidstream of the main liquid fuel is directed towards the combustionchamber. This additional direction is at an acute angle to the main axisand is directed towards the combustion chamber.

According to the invention, the at least one liquid fuel outlet is at aside of the injection side of the injection component. This ensures thata spray or a fluid stream of the main liquid fuel is directed towardsthe combustion chamber along an angle to the main axis. This directionis at an acute angle to the main axis and is directed towards thecombustion chamber. In a related embodiment, the injection componentincludes a second additional outlet configured to introduce the mainliquid fuel into the burner interior. The second additional outlet is atan end of the injection side of the injection component. This providesan additional direction, i.e. along the main axis, in which anadditional spray or an additional fluid stream of the main liquid fuelis directed towards the combustion chamber.

In another embodiment of the burner, the inlet section of the swirlerincludes at least one air inlet and at least one main fuel gas inlet.Thus the main gas fuel and the air from a compressor of the turbomachinemay be introduced into the burner interior separately at the swirler. Inan alternate embodiment, the main gas fuel and the air from thecompressor may be introduced via a common inlet.

In another embodiment of the burner, the at least one air inlet and/orthe at least one main fuel gas inlet is arranged tangentially along theswirler with respect to the main axis. This provides a commonly usedembodiment of the swirler and thus the burner of the present techniquemay be realized, operated and manufactured with ease.

In another embodiment of the burner, the swirler has a conical frustumshape having a top side and a bottom side. A cross-section of theconical frustum increases from the top side towards the bottom side. Thetop side is connected to the burner head and the bottom side isconnected to the pre-mixing section. This provides another commonly usedembodiment of the swirler and thus the burner of the present techniquemay be realized, operated and manufactured with ease.

In an embodiment, the premixed dual fuel burner may have a radial widthtaken in a radial direction in respect of an axis of the burner—of theinjection component that reduces over an axial distance D by only orless than D/10, advantageously less than D/15. In other embodiment theradial width may reduce by less than D/20.

In another embodiment of the burner, the premixing section has a part ofthe premixing section which surrounds the burner outlet of the premixingsection. The part of the premixing section includes an external pilot.The external pilot is configured to introduce a pilot fuel into thecombustion chamber. This aids in formation an external recirculationzone in the combustion chamber and thus aiding in lean combustion.Furthermore the present technique may be implemented in turbomachinesthat use Dry Low NO_(x) combustions.

BRIEF DESCRIPTION OF THE DRAWINGS

The present technique is further described hereinafter with reference toillustrated embodiments shown in the accompanying drawing, in which:

FIG. 1 schematically illustrates a cross-sectional view of an exemplaryembodiment of a premixed dual fuel burner including an injectioncomponent,

FIG. 2 schematically illustrates a cross-sectional view of the injectioncomponent of the embodiment depicted in FIG. 1,

FIG. 3 schematically illustrates a cross-sectional view of anotherexemplary embodiment of the premixed dual fuel burner including theinjection component,

FIG. 4 schematically illustrates a cross-sectional view of the injectioncomponent of the embodiment depicted in FIG. 3,

FIG. 5 schematically illustrates a cross-sectional view of an exemplaryembodiment of the premixed dual fuel burner depicting the injectioncomponent at a first position,

FIG. 6 schematically illustrates a cross-sectional view of an exemplaryembodiment of the premixed dual fuel burner depicting the injectioncomponent at a second position as compared to the first positiondepicted in FIG. 5, and

FIG. 7 schematically illustrates a cross-sectional view of an exemplaryembodiment of the premixed dual fuel burner depicting the injectioncomponent at another second position as compared to the first positiondepicted in FIG. 5 and the second position depicted in FIG. 6, inaccordance with the present technique.

DETAILED DESCRIPTION OF INVENTION

Hereinafter, above-mentioned and other features of the present techniqueare described in details. Various embodiments are described withreference to the drawing, wherein like reference numerals are used torefer to like elements throughout. In the following description, forpurpose of explanation, numerous specific details are set forth in orderto provide a thorough understanding of one or more embodiments. It maybe noted that the illustrated embodiments are intended to explain, andnot to limit the invention. It may be evident that such embodiments maybe practiced without these specific details.

It may be noted that in the present disclosure, the terms “first”,“second”, “another second” etc. are used herein only to facilitatediscussion, and carry no particular temporal or chronologicalsignificance unless otherwise indicated.

Referring to FIG. 1, a cross-sectional view of an exemplary embodimentof a premixed dual fuel burner 1, hereinafter referred to as the burner1 has been schematically represented. The burner 1 essentially uses atleast two main fuels a main gas fuel and a main liquid fuel in additionto and besides a pilot fuel and associated pilot fuel supply lines andtechniques.

The burner 1 includes a burner head 10, a burner interior 20, a swirler30, a premixing section 40 and an injection component 50. The burner 1is assembled in association with a combustion chamber 99 in aturbomachine (not shown) which work with dual fuel combustion reaction.The main fuel is combusted in the combustion chamber 99 in form of acombustion mixture after being mixed with an air from a compressorsection (now shown) of the turbomachine. The main gas fuel mixed withair and the main liquid fuel may be combusted in the combustion chamber99 separately or simultaneously.

The burner head 10 includes a burner head end 12. The swirler 30 isarranged in series between the burner head 10 and the premixing section40. The burner 1 has a main axis 9. The burner head 10, the swirler 30and the premixing section 40 are arranged along the main axis 9. Theswirler 30 is an elongated 3-dimensional body. When visualized as notintegrated as a part of the burner 1, the swirler 30 is open at bothends and has a side wall enclosing a volume or limiting a volume withinthe side wall and the open ends. Similarly, the premixing section 40 isan elongated 3-dimensional body. When visualized as not integrated as apart of the burner 1, the premixing section 40 is open at both ends andhas a side wall enclosing a volume or limiting a volume within the sidewall and the open ends.

However, when integrated as parts of the burner 1, and when arranged inseries such that the swirler 30 is positioned between the burner head 10and the premixing section 40, as depicted in FIG. 1, the volume enclosedby swirler 30 and the volume enclosed by the premixing section 40together form a volume referred to as the burner interior 20. Theswirler 30 may be connected to the burner head 10 by direct physicalcontact, as depicted in FIG. 1, or may be connected to the burner head10 through an intermediate piece (not shown) or a connecting region (notshown). Similarly, in the burner 1, the swirler 30 may be connected tothe premixing section 40 by direct physical contact with the premixingsection 40 or may be connected to the premixing section 40 through anintermediate connecting piece (not shown). The burner interior 20represents a total volume enclosed by the swirler 30 and the premixingsection 40 with burner head 10 at one end of the total volume and thecombustion chamber 99 at the other end of the total volume, either withor without one or more such intermediate connecting pieces.

The burner interior 20 is a volume or a hollow that is elongated alongthe main axis 9. The burner interior 20 is formed of an upstream side 22and a downstream side 24. The upstream side 22 is disposed between theburner head 10 and the downstream side 24. As depicted in FIG. 1, theupstream side 22 and the downstream side 24 may be understood as acontinuous volume, or in other words, the upstream side 22 is fluidlyconnected to the downstream side 24, i.e. the upstream side 22 and thedownstream side 24 are continuous and together form the burner interior20 in FIG. 1. A part of the burner interior 20 enclosed by the swirler30 is the upstream side 22 of the burner interior 20 and the other partof the burner interior 20 enclosed by the premixing section 40 is thedownstream side 24 of the burner interior 20.

As depicted in FIG. 1, in an exemplary embodiment of the burner 1, theswirler 30 is directly connected to or affixed to or assembled with theburner head end 12 of the burner head 10, and the swirler 30 is alsodirectly connected to or affixed to or assembled with the premixingsection 40. As shown in FIG. 1, the swirler 30 may be conically designedfor example having a conical frustum shape. The conical frustum shape ofthe swirler 30 has a top side 36 and a bottom side 38. A cross-sectionalarea of the bottom side 38 is greater than a cross-sectional area of thetop side 36, or in other words, a cross-section of the conical frustumincreases from the top side 36 towards the bottom side 38 along the mainaxis 9. The top side 36 is connected to the burner head end 12 of theburner head 10 and the bottom side 38 is connected to the pre-mixingsection 40.

The swirler 30 includes an inlet section 32. The inlet section 32 isfluidly connected to the compressor (not shown) of the turbomachine (notshown). The inlet section 32 receives compressed air from the compressorand introduces the compressed air into the burner interior 20, moreprecisely into the upstream side 22 of the burner interior 20.Similarly, the inlet section 32 is fluidly connected to a fuel supply(not shown) of the turbomachine. The inlet section 32 receives main gasfuel from the fuel supply and introduces the main gas fuel into theburner interior 20, more precisely into the upstream side 22 of theburner interior 20.

In an exemplary embodiment of the burner 1 as depicted in FIG. 1, theinlet section 32 of the swirler 30 includes at least one air inlet 33and at least one main fuel gas inlet 34. The compressed air isintroduced into the burner interior 20 via the air inlet 33 and the maingas fuel is introduced into the burner interior 20 via the main fuel gasinlet 34. The air inlet 33 may be tangentially arranged along theswirler 30 with respect to the main axis 9. Similarly, the main fuel gasinlet 34 may be tangentially arranged along the swirler 30 with respectto the main axis 9. For example, when the swirler 30 is conical frustumshaped, the air inlet 33 and/or the main fuel gas inlet 34 may be formedas longitudinally extending slots through a body wall (now shown) of theconical frustum. In an exemplary embodiment of the burner 1, the inletsection 32 includes a plurality of the air inlets 33 and a plurality ofthe main fuel gas inlets 34 arranged around the swirler 30 in adistributed way such that when the main gas fuel and the compressed airenter the burner interior 20 though the air inlets 33 and the main fuelgas inlets 34, a swirl is generated in the compressed air and the maingas fuel. Principle of swirl generation through longitudinal slots i.e.the air inlets 33 and the main fuel gas inlets 34, on such a conicalshaped swirler 30 is known in the art of turbomachines and thus notexplained in details herein for sake of brevity.

The premixing section 40 is an elongated tubular body. The premixingsection 40 has a burner outlet 42 through which the premixing section 40is arranged or fixed or assembled with the combustion chamber 99. Asseen in FIG. 1, in the burner 1 the burner outlet 42 of the premixingsection 40 is an opening through which the burner interior 20, moreprecisely the downstream side 24 of the burner interior 20 fluidlyconnects to the combustion chamber 99. Thus the burner interior 20 iscontinuous with the combustion chamber 99 through the burner outlet 42.The combustion mixture and/or its constituents flow from the swirler 30into the premixing section 40 and then into the combustion chamber 99though the burner outlet 42. The premixing section 40, also referred toas mixer 40, performs or allows the mixing of the compressed air and themain gas fuel.

The injection component 50 has a tapering structure positioned along themain axis 9. The tapering structure of the injection component 50extends from the burner head 12 into the burner interior 20. Theinjection component has a burner head side 52 and an injection side 54.The injection component 50 tapers from the burner head side 52 to theinjection side 54 along the main axis 9. The tapering means across-sectional area perpendicular to the main axis 9 of the injectioncomponent 50 decreases when moving from the head side 52 to theinjection side 54 along the main axis 9. In one embodiment the decreasein the cross-sectional area is gradual for example when the injectionbody 50 is designed like in form of a regular conical structure, as alsodepicted in FIG. 2.

The injection component 50 may be hollow for guiding fuel. Particularly,as the injection component 50 is tapered, the inner hollow space mayalso be tapered accordingly. So the fuel passage within the injectioncomponent 50 reduces in width along an axial direction of the taperedsection of the injection component 50.

As seen in FIG. 1 in combination with FIG. 2, the injection component 50includes at least one liquid fuel outlet 55 at the injection side 54. Amain liquid fuel is introduced into the burner interior 20 through theat least one liquid fuel outlet 55. The main liquid fuel may be fed tothe liquid fuel outlet 55 via fuel lines (not shown) formed inside theinjection body 50. The fuel lines within the injection component 50 mayin turn be connected to a liquid fuel supply (now shown) of theturbomachine. As depicted in FIG. 1, the injection side 54 of theinjection component 50 is disposed in the burner interior 20 as a freestanding manner i.e. without any physical supports at the injection side54. As seen in FIG. 1, the injection body 50, in an exemplary embodimentof the burner 1, is coaxially positioned with the main axis 9.

As shown in FIGS. 1 and 2, the at least one liquid fuel outlet 55 is ata side 58 of the injection side 54 of the injection component 50. In anexemplary embodiment of the burner 1, there are more than one liquidfuel outlets 55 located on the injection side 54 of the injectioncomponent 50, for example FIG. 1 shows two liquid fuel outlets 55, fromeach of the liquid fuel outlets 55 the main liquid fuel is discharged inform of a fluid stream or in atomized form with a direction towards thecombustion chamber 99, for example as depicted by arrows 71.Furthermore, as depicted in FIG. 2, the injection component 50 mayinclude a second additional outlet 62 which may have different shape orsize as compared to the liquid fuel outlet 55. The second additionaloutlet 62 is also used to introduce the main liquid fuel into the burnerinterior 20, albeit the second additional outlet 62 is at a differentposition on the injection side 54 for example an end 56 of the injectionside 54 of the injection component 50.

Referring now to FIGS. 3 and 4 that schematically illustrate across-sectional view of another exemplary embodiment of the burner 1. Asshown in FIGS. 3 and 4, the at least one liquid fuel outlet 55 is at anend 56 of the injection side 54 of the injection component 50. In anexemplary embodiment of the burner 1, there may be more than one liquidfuel outlets 55 located on the end 56 of the injection side 54 of theinjection component 50. FIG. 3 shows one liquid fuel outlet 55 fromwhich the main liquid fuel is discharged in form of a fluid stream or inatomized form with a direction towards the combustion chamber 99, forexample as depicted by arrow 71. Furthermore, as depicted in FIG. 4, theinjection component 50 may include a first additional outlet 61 whichmay have different shape or size as compared to the liquid fuel outlet55. FIG. 4 depicts two such first additional outlets 61. The additionaloutlet 61 is also used to introduce the main liquid fuel into the burnerinterior 20, albeit the first additional outlet 61 is at a differentposition on the injection side 54 for example a side 58 of the injectionside 54 of the injection component 50.

As can be seen in FIGS. 1 and 3, in both embodiments of the burner 1,due to the tapering structure of the injection component 50 which aidsin the axial flow of the air from the compressor and/or combustionmixture along the main axis 9 and due to injection of the main liquidfuel via the liquid fuel outlet 55 in a suitable position within thedownstream side 24 of the burner interior 20, formation of a centralrecirculation zone 4 in the combustion chamber 99 is achieved, andundesired formation of any recirculation zone extending into the burnerinterior 20 is obviated.

Furthermore, as seen in FIGS. 1 and 3, in the burner 1, the premixingsection 40 has a part 44 of the premixing section 40 that surrounds theburner outlet 42 of the premixing section 40. The part 44 includes anexternal pilot 45, as depicted in FIG. 1. From the external pilot 45, apilot fuel is introduced into the combustion chamber 99. FIGS. 1 and 3show introduction of the pilot fuel through the part 44 into thecombustion chamber 99. A direction of injection of the pilot fuel isdepicted by arrow 72 in FIGS. 1 and 3. It may be noted that though FIG.1 shows just one external pilot 45, it is well within the scope of thepresent technique that a plurality of the external pilots 45 are presentdistributed circumferentially around a body (not shown) of the premixingsection 40 around the burner outlet 42.

As depicted in FIGS. 1 and 3, in both embodiments of the burner 1, dueto the external pilot 45 and the ejection of the pilot fuel from theexternal pilot 45 in the direction 72, formation of an externalrecirculation zone 5 in the combustion chamber 99 is achieved. Inexemplary embodiment of the burner 1, the external recirculation zone 5surrounds the central recirculation zone 4 annularly and helps tofurther stabilize the central recirculation zone 4.

Now referring to FIGS. 5, 6 and 7, different positions of the injectioncomponent 50 along the main axis 9 are depicted. As seen in FIG. 5, inan embodiment of the burner 1, the liquid fuel outlet 55 is positionedin the downstream side 24 of the burner interior 20. Similarly, as seenin FIG. 6, in another embodiment of the burner 1, the liquid fuel outlet55 is positioned in the downstream side 24 of the burner interior 20albeit in a different position with respect to the position of theliquid fuel outlet 55 of FIG. 5. Alternatively, as seen in FIG. 7, in analternate embodiment of the burner 1, the liquid fuel outlet 55 ispositioned in the upstream side 22 of the burner interior 20.

As depicted in FIGS. 1, 3 and 5, a first distance 91 is a distance alongthe main axis 9 between the at least one liquid fuel outlet 55 and theburner head end 12, and a second distance 92 is a distance along themain axis 9 between the burner outlet 42 of the premixing section 40 andthe burner head end 12. In embodiments of the burner 1, where there aremore than one liquid fuel outlets 55, the first length 91 is calculatedas a mathematical average of all the distances of each individual liquidfuel outlets 55 from the burner head end 12. In other embodiments of theburner 1, as depicted in way of exemplary embodiments of FIGS. 5, 6 and7 mainly, a ratio of the first distance 91 and the second distance 92may vary, for example the first distance 91 may be between 20% and 80%of the second distance 92 along the main axis 9.

Furthermore, in one embodiment of the burner 1, the injection component50 is longitudinally adjustable or moveable along the central axis 9,such that a position of the at least one liquid fuel outlet 55 of theinjection component 50 gets changed from a first location 93, asdepicted in FIG. 5 along the main axis 9 to a second location 94 alongthe main axis 9, as depicted in FIG. 6. Thus the injection component 50is retractable into the burner interior 20 from the combustor chamberoutlet 42 towards the burner head 10 and/or is extendable into theburner interior 20 from burner head 10 towards the combustor chamberoutlet 42.

Furthermore, as depicted from a combination of FIGS. 5, 6 and 7, it canbeen seen that the injection component 50 has progressively retractedinto the burner interior 20 from the combustor chamber outlet 42 towardsthe burner head 10 gradually from FIGS. 5 to 7. FIG. 7 shows anothersecond location 94 depicted in FIG. 7 as compared to the second location94 of FIG. 6 and as compared to the first location 93 of FIG. 5.

The shape of a fuel lance—i.e. the injection component 50—is tapered ina way, that the fuel lance is an elongated component. Advantageously itmay reduce its width taken in radial direction along an axial distance Donly by or less than D/10, advantageously less than D/20.

While the present technique has been described in detail with referenceto certain embodiments, it should be appreciated that the presenttechnique is not limited to those precise embodiments. Rather, in viewof the present disclosure which describes exemplary modes for practicingthe invention, many modifications and variations would presentthemselves, to those skilled in the art without departing from the scopeand spirit of this invention. The scope of the invention is, therefore,indicated by the following claims rather than by the foregoingdescription. All changes, modifications, and variations coming withinthe meaning and range of equivalency of the claims are to be consideredwithin their scope.

1. A premixed dual fuel burner for a combustion chamber of aturbomachine, the premixed dual fuel burner comprising: a burner headhaving a burner head end, a burner interior elongated along a main axisand having an upstream side and a downstream side, wherein the upstreamside is disposed between the burner head and the downstream side andwherein the upstream side is fluidly connected to the downstream side, aswirler enclosing the upstream side of the burner interior andcomprising an inlet section configured to introduce air and a main gasfuel into the burner interior, a premixing section enclosing thedownstream side of the burner interior, wherein the swirler is arrangedbetween the burner head and the premixing section, and wherein thepremixing section comprises a burner outlet configured to be arrangedwith the combustion chamber such that the downstream side is fluidlyconnected to the combustion chamber, and an injection component having atapering structure positioned along the main axis and extending from theburner head into the burner interior, the injection component having aburner head side and an injection side and wherein the injectioncomponent tapers from the burner head side to the injection side alongthe main axis, wherein the injection component comprises at least oneliquid fuel outlet at the injection side and the injection component isconfigured to introduce a main liquid fuel into the burner interiorthrough the at least one liquid fuel outlet and wherein the injectionside of the injection component is disposed in the burner interior, andwherein at least one of the at least one liquid fuel outlet is at a sideof the injection side of the injection component.
 2. The premixed dualfuel burner according to claim 1, wherein the tapering structure of theinjection component is a conical structure.
 3. The premixed dual fuelburner according to claim 1, wherein the tapering structure of theinjection component is arranged coaxially to the main axis.
 4. Thepremixed dual fuel burner according to claim 1, wherein a first distancealong the main axis between the at least one liquid fuel outlet and theburner head end is between 20% and 80% of a second distance along themain axis between the burner outlet of the premixing section and theburner head end.
 5. The premixed dual fuel burner according to claim 1,wherein the injection component is configured to be longitudinallyadjustable such that a position of the at least one liquid fuel outletof the injection component is changeable from a first location along themain axis to a second location along the main axis.
 6. The premixed dualfuel burner according to claim 1, wherein the at least one liquid fueloutlet is positioned in the upstream side of the burner interior.
 7. Thepremixed dual fuel burner according to claim 1, wherein the at least oneliquid fuel outlet is positioned in the downstream side of the burnerinterior.
 8. The premixed dual fuel burner according to claim 1, whereinthe injection component comprises a second additional outlet configuredto introduce the main liquid fuel into the burner interior and whereinthe second additional outlet is at an end of the injection side,particularly at a tip, of the injection component.
 9. The premixed dualfuel burner according to claim 1, wherein the inlet section of theswirler comprises at least one air inlet and at least one main fuel gasinlet.
 10. The premixed dual fuel burner according to claim 9, whereinat least one of the at least one air inlet and the at least one mainfuel gas inlet is arranged tangentially along the swirler with respectto the main axis.
 11. The premixed dual fuel burner according to claim1, wherein the swirler has a conical frustum shape having a top side anda bottom side and wherein a cross-section of the conical frustumincreases from the top side towards the bottom side and wherein the topside is connected to the burner head and the bottom side is connected tothe pre-mixing section.
 12. The premixed dual fuel burner according toclaim 1, wherein a part of the premixing section surrounding the burneroutlet of the premixing section comprises an external pilot configuredto introduce a pilot fuel into the combustion chamber.
 13. The premixeddual fuel burner according to claim 1, wherein a radial width of theinjection component reduces over an axial distance D by only or lessthan D/10.
 14. The premixed dual fuel burner according to claim 1,wherein a radial width of the injection component reduces over an axialdistance D by only or less than D/15.